Don't bug out: Cicadas are coming

Periodical cicadas, living underground since the Clinton administration, getting ready to emerge.

April 09, 2013|By Daniel Patrick Sheehan, Of The Morning Call

The cicadas that will emerge across the Lehigh Valley in coming weeks as the weather grows warmer are sure to raise a racket, because that's what cicadas are best at.

But you'd probably raise one too, if you'd been living underground for 17 years.

Yup — 1996. That's when the last generation of this particular brood of periodical cicadas — known as Brood II — came out of the ground, mated, laid eggs in the trees and died.

The eggs hatched into nymphs that dropped from the trees and burrowed into the soil, from a couple of inches to a couple of feet deep.

And ever since then — through the last reign of a New York Yankees dynasty, through the Bush-Gore election debacle, through the advent of Google and Facebook, through the Iraq War and the entire run of "The Daily Show" — those nymphs have been preparing for this spring, when they will creep back to daylight and start the whole raucous cycle over again.

"It's one of the great stories of nature," said Marten Edwards, an associate biology professor at Muhlenberg College in Allentown.

His sense of excitement is mounting as he anticipates the cicadas' arrival — probably sometime in May, depending on soil temperatures — and the chance to gather new data about their population density and spread.

"The last time these came out was when Bill Clinton was president," Edwards said. "And they'll come out again in 2030."

Periodical cicadas live only in the eastern half of North America, unlike the annual, or dog-day, cicadas that appear every year and are found around the world.

Periodicals have red eyes, fat bodies and broad wings. American colonists thought they were locusts, of the kind that brought grief to Egypt in the biblical plague, but they aren't. Locusts are a kind of grasshopper.

They emerge, often in the course of a single day and night, when the soil temperature 8 inches deep reaches 64 degrees. Because until this week the spring has been so cool, Edwards said he would be surprised to see them before the first week of May.

In a heavy infestation, more than 1.5 million cicadas will infest a single acre. The males shriek like rusty door hinges — it's their mating call — and a big gathering in full chorus can reach the decibel level of a jackhammer and drown out just about every other sound.

Edwards said a female responds to an attractive male with a come-hither wing click, and that's when the next generation of cicadas gets started.

The cicada life cycle is the longest in the insect world. The bugs are slow and clumsy and have no poison or sting, so they are helpless against the birds, squirrels and other creatures that love to feast on them.

Their only defense is sheer numbers. It's called "predator satiation" — there are so many cicadas, predators can't possibly eat them all, so the species continues.

"They'll fill up the bellies of anyone who wants to eat them," Edwards said. "You'll see dogs eat them until they throw up, and then they'll eat some more."

So, the gist of this story is that red-eyed bugs will swarm by the millions — or billions, who's counting? — and there's not much you can do about it.

"I do not recommend insecticides to kill them," said Emelie Swackhamer, a horticulture educator with the Penn State Extension. "Even if you knock down some of them, I don't know how much effectiveness you have."

Besides, they're pretty harmless, as bugs go. Cicadas do little damage, because they feed on sap, not leaves or roots.

Their egg laying, however, can be a problem, because females cut slits in twigs to deposit the eggs. In a major infestation, that can cause branches to die and leaves to brown and fall.

Swackhamer said they favor fruit trees. She recommended covering these — and younger trees of any variety, which will be more vulnerable to slitting — with fabric to keep the cicadas off after they emerge.

The aesthetic problem is something else.

"I will definitely have to take some steps," said wedding planner Sharon Dickinson of An Affair to Remember, who has an outdoor wedding scheduled for May in Bethlehem and dreads the idea of the wedding band competing with a cicada chorus. "We may have to get some sort of amplifier system."

There are 12 broods of 17-year cicadas and three broods on a 13-year schedule. The last major emergence in this area was Brood X, a 17-year brood, in 2004.

As in other years, the populations were patchy, so some areas reported heavy infestations, with cicada corpses — they live about a month — piling up like snow. Other areas had hardly any bugs at all.

This year, Edwards and his students will compile GPS data on the bugs, so when they return in 2030, scientists will have precise coordinates for the populations.

People who saw heavy infestations in the 2004 emergence probably won't see one this time around.

"They generally don't overlap at all," he said. "You'll either have Brood X or Brood II."